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In this paper a novel numerical methodology for calculating non-uniform residual stress distributions during the glass tempering process is presented. Tempering techniques lead to non-uniform heat transfer rates causing residual stress inhomogeneities, which consequently have a direct impact on the structural behaviour of components. Nevertheless, most works in the literature do not consider the influence of local flow phenomena during thermal calculations, resulting in non-representative residual stress distributions. In this context, a novel generalised methodology based on a fluid–structure interaction one-way approach to sequentially couple the thermal and mechanical fields is presented. In this way, the unsteady and non-uniform heat transfer rate is coupled with the Narayanaswamy model to predict the non-homogeneous residual stress pattern. The obtained numerical results for the analysed impinging jet array case are in good agreement both quantitatively and qualitatively, exhibiting an average error below 10% with respect to previous experimental investigations. Finally, efforts are made to reduce the computational time. Therefore, the proposed methodology proves to be an efficient tool for understanding the underlying mechanisms and predicting the residual stress distributions during glass tempering.

The protection of the viral genome during extracellular transport is an absolute requirement for virus survival and replication. In addition to the almost universal proteinaceous capsids, certain viruses add a membrane layer that encloses their double-stranded (ds) DNA genome within the protein shell. Using the membrane-containing enterobacterial virus PRD1 as a prototype, and a combination of nanoindentation assays by atomic force microscopy and finite element modelling, we show that PRD1 provides a greater stability against mechanical stress than that achieved by the majority of dsDNA icosahedral viruses that lack a membrane. We propose that the combination of a stiff and brittle proteinaceous shell coupled with a soft and compliant membrane vesicle yields a tough composite nanomaterial well-suited to protect the viral DNA during extracellular transport.

Gas metal arc welding (GMAW) is one of the most used joining method in the industry. However, one of the main problems of this process is the generation of residual stresses which have direct impact on the fatigue life of welded components. Nevertheless, residual stress pattern prediction is complex and requires the simulation of the welding process. Currently, there are different numerical methods to predict the residual stresses generated in GMAW process, being Goldak’s method one of the most widely used model. However, the main limitation of these methods is that they require defining many parameters experimentally and, consequently, this method is not valid during design process. Alternatively, in this work, it is developed a procedure where the heat source is defined based on the welding physics for spray transfer welding. The developed procedure has been validated for a spray transfer multipass butt weld case. Results have shown good correspondence with an average deviation of 9.16 % in thermal field and 42 MPa in the final residual stress field. Thus, the developed procedure has been validated as a cost-effective alternative method to estimate residual stress pattern in spray transfer multipass welding. Furthermore, the developed method does not require any welding experimental characterization once the efficiency of the used welding machine is defined. The proposed method can be used as a valid tool to optimize the welding process in order to minimize the residual stress field and, consequently, improve the fatigue life.

Nowadays, the requirements demanded to many of the parts used in such industries as the aeronautic or the automotive industry are increasingly higher: more complex shapes, previously unimaginable, lower and lower radii, impossible geometries, etc., all of this combined with high values of mechanical strength, corrosion resistance, impact absorption, fatigue resistance, etc. In addition, the increasingly more severe environmental regulations regarding the minimization of the CO2 emissions as well as the increase in energetic efficiency claim for lightweight materials able to lighten the currently known structures without penalizing their mechanical properties, i.e., materials of high specific mechanical properties. High specific strength steels, some aluminium alloys and some magnesium alloys are within this category. All of these materials answer properly the requirements of high mechanical properties and low weight; however, all of them exhibit a low formability at room temperature, so they are not able to answer the current geometric requirements. To answer both requirements simultaneously (high mechanical properties and complex geometries), new advanced forming process to manufacture materials of high mechanical properties have been researched; that is the case of the hydroforming processes. Strategies of increasing forming temperature are used in order to increase the formability of the materials of high specific strength; in the case of the previously mentioned processes, this leads to the so-called Warm Hydroforming (WH). It is a process currently under research so the development and improvement possibilities are many: identification of optimal process parameters, development of working methodologies, optimization of process times, identification of process control strategies, etc. Thereby, this thesis answers some of those development and improvement possibilities of Warm Tube Hydroforming processes (WTHF); the research is focused on the application of those, Gaur egun, aeronautika eta automobilgintza sektoreetan erabiltzen diren pieza askori eskatzen zaizkien eskakizunak geroz eta zorrotzagoak dira: geroz eta forma konplexuagoak, lehen imajinaezinak, geroz eta erradio nabarmenagoak, ezinezko geometriak… Horri guztiari beste hauek ere gehitu behar zaizkio: erresistentzia mekaniko altua, korrosioarekiko erresistentzia, inpaktu xurgatzea, nekearekiko erresistentzia… Halaber, CO2 isurketak gutxitzera eta energi eraginkortasuna hobetzera bideratutako ingurumen arauek pisu gutxiko materialak eskatzen dituzte, gaur egun ezagutzen ditugun egiturak arintzeko gai izango direnak, baina propietate mekanikoak galdu gabe: erresistentzia espezifiko handiko materialak. Hain zuzen ere, azken multzo horren barruan erresistentzia handiko altzairuak, hainbat aluminio aleazio eta hainbat magnesio aleazio daude. Material horiek guztiek egoki erantzuten dizkiete propietate mekaniko handiak eta pisu gutxi izateko eskakizunei; aitzitik, giro tenperaturan konformagarritasun txikia dute eta ondorioz, ez dira gai gaur egungo eskakizun geometrikoei erantzuteko. Bi eskakizun hauei batera erantzun ahal izateko (propietate mekaniko handiak eta geometria konplexuak), propietate mekaniko handiko materialen transformaziorako konformazio prozesu aurreratuak ikertu izan dira (eta ikertzen ari dira); hidrokonformazio prozesuaren kasua adibidez. Erresistentzia espezifiko handiko materialen eta konformagarritasuna handitzeko erabiltzen den estrategia, konformazio tenperaturaren igotzea dira. Aurretik aipatutako prozesuen kasuan honek, tenperatura moderatuetan hidrokonformazio izena hartzen du. Gaur egun, ikerketa fasean dagoen prozesu bat denez, garapen eta hobekuntza aukerak asko dira, hala nola: prozesuetako parametro hoberenak identifikatzea, lan metodologien garapena, teknologia honen bidez konformatu daitezkeen material hoberenak identifikatzea, prozesu zikloen optimizazioa, prozesua kontrolatzeko estrategiak identifikatzea,… Zentzu honetan, tesi honek W, Hoy en día, los requerimientos exigidos a muchas de las piezas empleadas en sectores tales como el aeronáutico o el de automoción son cada vez mayores: formas cada vez más complejas, anteriormente inimaginables, radios cada vez más pronunciados, geometrías imposibles,… todo esto unido a elevados valores de resistencia mecánica, resistencia a la corrosión, absorción de impacto, resistencia a fatiga,… Asimismo, las cada vez más exigentes normativas medioambientales relativas a la reducción de emisiones de CO2 así como al incremento de la eficiencia energética, demandan materiales de bajo peso capaces de aligerar las estructuras actualmente conocidas sin detrimento de sus propiedades mecánicas, es decir, materiales de elevada resistencia específica. Dentro de este último grupo se encuentran los aceros de alta resistencia, ciertas aleaciones de aluminio y ciertas aleaciones de magnesio. Todos estos materiales responden adecuadamente a los requerimientos de elevadas propiedades mecánicas y bajo peso; sin embargo, todos ellos presentan una baja conformabilidad a temperatura ambiente, con lo que no son capaces de responder a los requerimientos geométricos actuales. Para conseguir dar respuesta a ambos requerimientos simultáneamente (elevadas propiedades mecánicas y geometrías complejas), nuevos procesos de conformado avanzados para la transformación de materiales de elevadas propiedades mecánicas han sido (y siguen siendo) investigados; tal es el caso de los procesos de hidroconformado. Para elevar la conformabilidad de los materiales de elevada resistencia específica se acude a estrategias de aumento de la temperatura de conformado; en el caso de los procesos anteriormente mencionados, esto da lugar a lo que se conoce como hidroconformado a temperaturas moderadas. Por tratarse de un proceso actualmente en fase de investigación, las posibilidades de desarrollo y mejora son varias, entre ellas: identificación de parámetros de proceso óptimos, desarrollo de metodologías de t